A tomography apparatus for an eye portion such as an OCT (Optical Coherence Tomography) allows to three-dimensionally observe the state of the interior of retina layers. In recent years, this tomography apparatus for an eye portion has received a lot of attention since it is effective to give more adequate diagnoses of diseases.
FIG. 3A illustrates tomograms of a retina captured by the OCT. Referring to FIG. 3A, reference symbols T1 to Tn denote two-dimensional tomograms (B-scan images) of a macular region. Reference symbol D denotes an optic nerve papilla; and M, a macular region. Reference numeral 1 denotes an inner limiting membrane; 2, a boundary between a nerve fiber layer and its underlying layer (to be referred to as a nerve fiber layer boundary 2 hereinafter); and 2′, a nerve fiber layer. Reference numeral 3 denotes a boundary between an inner plexiform layer and its underlying layer (to be referred to as an inner plexiform layer boundary 3 hereinafter); and 4, a boundary between an outer plexiform layer and its underlying layer (to be referred to as an outer plexiform layer boundary 4 hereinafter). Reference numeral 5 denotes a junction between inner and outer photoreceptor segments; 6, a retinal pigment epithelial layer boundary; and 6′, a retinal pigment epithelial layer edge. For example, when such tomograms are input, if the thickness (TT1 in FIG. 3A) of the nerve fiber layer 2′ can be measured, a degree of progress of a disease such as glaucoma and a recovery level after a medical treatment can be quantitatively diagnosed. In order to judge the progress states and recovery levels of medial treatment effects of diseases of an eye portion, a technique which facilitates comparison operations using a display mode that allows an operator to recognize the mutual relationship between a fundus image and tomograms obtained by the OCT has been disclosed (see Japanese Patent Laid-Open No. 2008-073099).
However, Japanese Patent Laid-Open No. 2008-073099 described above displays an OCT tomogram and layer boundaries corresponding to a position designated on a fundus image, but it merely displays a tomogram and its boundaries at a position designated by a doctor. For this reason, the doctor may often dither to judge about whether a portion having an abnormal layer thickness in the tomogram at the designated position is caused by an individual feature or a disease.